Here's how something like this cropped up in another game.
The skinner, with each passing day, is becoming more like a battlebabe, and so the change in playbooks is only a matter of time. When she started out, she was established as having a guitar, and she would put on performances, playing guitar and singing, for her Artful & Gracious move. When she flips to battlebabe (because again, it's a when, not an if), then, does she have to give up her guitar, like the driver has to give up his vehicle? Well, that seems odd, if the playbook change necessitates the loss of the instrument. But I could see her purposely choosing to give up her guitar, to signify her change in being. She's a battlebabe now, not a musician.
However, it has become more apparent now that her singing is a signficant part of her Artful & Gracious move, her chosen art. So...if she becomes a battlebabe, does she have to give up her singing voice? That's hyperbolic, of course, but it might be better understood as, "if the Artful & Gracious move was, for her, a core component of being a Skinner, does she have to essentially give up everything attached to that move? Does she have to give up the move itself? Maybe when she becomes a battlebabe, her chosen art changes to something like 'combat' or 'doing murders' or some other good old cliche?"
I think that what this illustrates to me is that the context thing of what makes sense to abandon actually goes one step further. The choice of what this character does abandon is so much more telling than saying "She has to abandon her guitar, she has to abandon her position as a singer in the club." Something needs to have changed, certainly, to get across that she's a battlebabe now, and not a skinner. But to me, the responsibility to portray that shift does not fall on some prescriptive "give up these pieces of equipment" thing; it's much stronger if it's embodied in a specific choice, made by the character (and the player).
So maybe that's one possible answer. Does Annette have to give up Bus? Well, no, not necessarily. But Annette does have to have changed in some fashion, so that she's not who she was before. The exact form of that change is up to you, so long as it's there.
It's more like asking a penetrating question, "How did you change?", as opposed to saying, "CHANGE, DAMMIT!"
Also, Scott, that's a really interesting as a custom move, but it worries me with regard to some of the moves that are harder to use. Would Moonlighting be a move, for instance? How about Insano Like Drano? How about Oftener Right, which relies on other people coming to you, as opposed to you doing anything? How about Touched by Death? I could see this move working well in some games, then, where everyone's okay with losing some of these long-term moves as part of the attrition of switching playbooks, but I could totally see other games where this move would not work at all. Still, really cool to ponder, neat stuff.